Journal of Stored Products Research 36 (2000) 245±252 www.elsevier.com/locate/jspr

An illustrated identi®cation key to four di€erent species of adult (Coleoptera: ), commonly attacking dried cassava chips in West Africa

Kerstin SchaÈ fer a, b, Georg Goergen b, Christian Borgemeister a, b,*

aInstitute of Plant Diseases and Plant Protection, University of Hanover, HerrenhaÈuser Str. 2, 30419 Hanover, Germany bInternational Institute of Tropical Agriculture, Plant Health Management Division, 08 B.P. 0932, Cotonou, Benin Accepted 27 July 1999

Abstract

Bostrichids of the genus Dinoderus are commonly found as pests of dried cassava chips in West Africa. An illustrated key facilitating the identi®cation of the four most frequent African species, i.e. D. bifoveolatus (Wollaston), D. minutus (Fabricius), D. porcellus Lesne, and D. oblongopunctatus Lesne is presented. 7 2000 Elsevier Science Ltd. All rights reserved.

Keywords: Dinoderus bifoveolatus; D. minutus; D. porcellus; D. oblongopunctatus; Bostrichidae; Stored products; Tax- onomy

1. Introduction

Cassava (Manihot esculenta Crantz, Euphorbiaceae) constitutes one of the main staple foods in sub-Saharan Africa and is consumed in a variety of forms. In West Africa, cassava is mainly stored as dried sliced parts of the root, the so-called cassava chips. For instance, in Togo 120,000 to 150,000 t of cassava chips are produced annually (Adam, 1988), and most are stored. The bostrichids Dinoderus spp and Prostephanus truncatus (Horn) are important storage pests of cassava chips in tropical Africa (Nyakunga, 1982; Hodges et al., 1985). In Tanzania losses of 73% on fermented and of 52% on unfermented cassava chips were recorded after a

* Corresponding author. Tel.: +49-511-7622643; fax: +49-511-7623015. E-mail address: [email protected] (C. Borgemeister).

0022-474X/00/$ - see front matter 7 2000 Elsevier Science Ltd. All rights reserved. PII: S0022-474X(99)00046-6 246 K. SchaÈfer et al. / Journal of Stored Products Research 36 (2000) 245±252 four-month storage period (Hodges et al., 1985). In Ghana, both Dinoderus spp and P. truncatus have been found attacking stored products on farms (Rees, 1991). However, due to the dicult of Dinoderus spp, in most ®eld studies no information is given at species level (e.g., Wright et al., 1993). Sampling of cassava chips at local markets in Cotonou, Republic of Benin, and the subsequent identi®cation of the pest complex found, revealed that Dinoderus spp were predominant. Four di€erent species were identi®ed, namely D. bifoveolatus (Wollaston), D. minutus (Fabricius), D. porcellus Lesne, and D. oblongopunctatus Lesne (SchaÈ fer, 1998). An illustrated identi®cation key, which will enable ®eld workers to distinguish these four Dinoderus spp in West Africa, is presented.

1.1. Genus Dinoderus Stephens, 1830

Diagnosis: short bodied species. Frons very short with fronto-clypeal suture indistinct. Second antennal segment shorter than 1st. Antenna with 9±11 segments; all known African species with 10 antennal segments. Last visible abdominal segment curved to receive the pygidium. Lateral margin of pronotum with a carina present becoming sometimes indistinct at the anterior corner. Anterior margin of pronotum with a row of teeth occasionally interrupted medially. Posterior surface of the pronotum punctured. Elytra lacking subapical carina. Fore- tarsus with ®fth segment sub-equal in length to segments one to four together.

2. Key to common West African Dinoderus species

1. Pronotum with an obvious pair of fovae (depressions) near base 2 (Figs. 1, 11 and 13); elytra with or without ocellate punctures (see below) Ð Pronotum without fovae 3 (Figs. 2, 12 and 14); elytra without ocellate punctures 2. Elytra, including apical declivity, with simple punctures (base ¯at) bifoveolatus (Fig. 3); anterior part of elytra bare (Fig. 7); pronotum appearing longer (Fig. 11) (2±3.3 mm) Ð Elytra with ocellate punctures (middle of base raised) (Fig. 4), minutus particularly obvious on apical declivity; elytra pubescent throughout (Fig. 8) although pubescence may be missing in rubbed specimens; pronotum appearing shorter (Fig. 13) (2±3.7 mm) 3. Pronotum with posterolateral carina reaching ®rst row of marginal porcellus teeth (Fig. 9); dorsal puncturation of elytra consisting of large round punctures (Fig. 5) (2.7±3.5 mm) Ð Pronotum with posterolateral carina ending distinctly below ®rst row oblongopunctatus of marginal teeth (Fig. 10); dorsal puncturation of elytra narrow and oblong (Fig. 6) (2.7±3.3 mm) K. SchaÈfer et al. / Journal of Stored Products Research 36 (2000) 245±252 247

Figs. 1±6. 1, D. minutus, top view of the pronotum with shallow depressions; 2, D. oblongopunctatus; top view of the pronotum; puncturation of apical declivity; 3, D. bifoveolatus;4,D. minutus; puncturation of elytra; 5, D. porcellus; 6, D. oblongopunctatus. 248 K. SchaÈfer et al. / Journal of Stored Products Research 36 (2000) 245±252

Figs. 7±10. 7, D. bifoveolatus, dorsal surface of elytra; 8, D. porcellus, dorsal surface of elytra; 9, D. procellus, head lateral view with pronotal carina; 10, D. oblongopunctatus, head lateral view showing interrupted pronotal carina. K. SchaÈfer et al. / Journal of Stored Products Research 36 (2000) 245±252 249

Figs. 11±14. 11, Habitus pictures: D. bifoveolatus; 12, Habitus pictures: D. porcellus; 13, Habitus pictures: D. minutus; 14, Habitus pictures: D. oblongopunctatus. 250 K. SchaÈfer et al. / Journal of Stored Products Research 36 (2000) 245±252

2.1. Dinoderus bifoveolatus (Wollaston) Figs. 3, 7, 11

Rhyzopertha bifoveolata Wollaston, 1858 Dinoderus perpunctatus Lesne, 1895 Dinoderus bifoveolatus (Wollaston): Lesne, 1897 Material examined: BENIN: Allada, IX. 1995, on dried teakwood, n = 1 G. Goergen; BENIN: Cotonou, IX. 1997, on cassava chips, n = 65, K. SchaÈ fer; BENIN: Tchaourou, XI. 1997, on yam chips, n = 1275, P. Vernier; CAMEROON: Mengomo, II. 1997, on cassava chips, n =8, G. Goergen.

2.2. (Fabricius) Figs. 1, 4, 13

Apate minutus Fabricius, 1775 Dinoderus substriatus Stephens, 1830 Bostrichus vertens Walker, 1859 Rhizopertha sicula Baudi, 1873 Matsumura, 1915 Dinoderus minutus (Fabricius): Lesne, 1897 Material examined: BENIN: Cotonou, IX. 1997, on cassava chips, n = 6, K. SchaÈ fer; BENIN: Parakou, X. 1995, on dried yam, n = 5, P. Vernier; GHANA: Kpeve, X. 1994, on bamboo, n = 16, K. Acquaye; NIGERIA: Ibadan, I. 1997, stored maize, n = 3, B. R. Critchley, TOGO: Kloto forest, VII. 1995, on tree bark, n = 1, K. G. Goergen.

2.3. Dinoderus oblongopunctatus Lesne Figs. 2, 6, 10, 14

Dinoderus oblongopunctatus Lesne, 1923 Material examined: BENIN: Cotonou, X. 1997, on cassava chips, n = 10, K. SchaÈ fer; BENIN: Cotonou, IX. 1995, on dried yam, P. Vernier; BENIN: Parakou, X. 1995, on dried yam, n = 25, P. Vernier.

2.4. Dinoderus porcellus Lesne Figs. 5, 8, 9, 12

Dinoderus porcellus Lesne, 1923 Material examined: BENIN: Cotonou, X. 1997, on cassava chips, n = 509, K. SchaÈ fer; BENIN: Tchaourou, XI, 1997, on yam chips, n = 1742, P. Vernier; BENIN: Tchatchou, IV. 1994, on cassava chips, n = 17, S. SaõÈ zonou.

3. Discussion

The genus Dinoderus comprises, to date, 26 recognised species of which three are endemic to K. SchaÈfer et al. / Journal of Stored Products Research 36 (2000) 245±252 251 tropical Africa (D. oblongopunctatus, D. porcellus and D. gabonicus ) and two being of pan- tropical distribution (D. minutus and D. bifoveolatus ) (Lesne, 1938; Vrydagh, 1955). Since the major taxonomic work of Lesne (1924) there has been one particularly useful study on Dinoderus by Vrydagh (1955). This is largely based on Lesne's contributions (1897, 1924) and includes a key to all presently known species with descriptive notes on them. The most recent study on tropical storage by Delobel and Tran (1993) refers to Lesne's publications and those of Vrydagh in the chapter of Bostrichidae, and fully describes D. minutus and D. bifoveolatus but D. oblongopunctatus and D. porcellus are only brie¯y mentioned. Other keys such as the ones by Beiriger and Sites (1996), Spilman (1982) or Fisher (1950) cover mainly the North American bostrichid fauna. Since the Spilman (1982) and Fisher (1950) keys also include most species found in imported commodities, they are, with some limitations, also useful for the identi®cation of species commonly occurring on stored products in tropical Africa. The key presented here includes all known African species with the exception of D. gabonicus, which has a distribution area limited to southern Gabon. The characters utilised here refer to those used by Lesne, Vrydagh and the authors mentioned above. The common occurrence of four bostrichid species in the market of Cotonou is possibly due to the con¯uence of a large array of commodities and woody material that are often conveyed from long distances within the whole sub-region. The authors hope that the present key will greatly facilitate the identi®cation of Dinoderus spp, and will help ®eld workers, for instance during surveys, to collect more detailed information on the pest fauna of cassava stores and of other commodities (Osuji, 1980) in West Africa.

Acknowledgements

This work was conducted within the framework of projects funded by the German Ministry for Economic Co-operation and Development (BMZ) and the Danish International Development Agency (DANIDA), in close collaboration with the museum of the Plant Health Management Division of the International Institute of Tropical Agriculture (IITA) in Benin. Biosystematic and biodiversity research at IITA is supported by the Austrian government.

References

Adam, F. 1988. Pre sentation du Togo. In: Proceedings of the Regional African Workshop on the Containment and Control of Larger Grain Borer, Report III, Arusha, Tanzania, pp. 73±88. Beiriger, R., Sites, R., 1996. The Bostrichidae (Coleoptera) of Missouri. Journal of the Kansas Entomological Society 69, 45±68. Delobel, A., Tran, M. 1993. Les Cole opteÁ res des denre es alimentaires entrepose es dans les regions chaudes. In: Faune tropicale XXXII. Editions Orstom/CTA, CTA Wageninugen, pp. 95±106. Fisher, W.S., 1950. A revision of the North American species of beetles belonging to the family Bostrichidae. United States Department of Agriculture, Washington, DC, p. 157, Miscellaneous Publications No. 698. Hodges, R.J., Meik, J., Denton, H., 1985. Infestation of dried cassava (Manihot esculenta Crantz) by Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae). Journal of Stored Products Research 21, 73±77. 252 K. SchaÈfer et al. / Journal of Stored Products Research 36 (2000) 245±252

Lesne, P., 1897. Revision des coleopteÁ res de la famille des Bostrychides, 2eÁ me me moire. Bostrychides hypocephales. . Annales de la Socie te Entomologique de France 66, 319±350. Lesne, P. 1924. Les Cole opteÁ res Bostrychides de l'Afrique tropicale franc° ais. In: Encyclope die Entomologique III. Les Presses Universitaires de France, Paris, p. 301. Lesne, P. 1938. Bostrichidae. Junk Coleopterorum Catalogues 10, Part 161: 3±5, 18±84. Nyakunga, Y.B. 1982. The biology of Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae) on cassava. MSc Thesis, University of Reading, UK, 64 pp. Osuji, F.N.C., 1980. Observations on beetles attacking dried yams and yam ¯our from three Nigerian markets. Tropical Stored Products Information 39, 35±38. Rees, D.P., 1991. The e€ect of Teretriosoma nigrescens Lewis (Coleoptera: Histeridae) on three species of storage Bostrichidae infesting shelled maize. Journal of Stored Products Research 27, 83±86. SchaÈ fer, K. 1998. Host-®nding behaviour in bostrichids with particular reference to Dinoderus bifoveolatus Wollaston (Coleoptera: Bostrichidae), a pest of stored cassava. MSc thesis, University of Hannover, Germany, 77 pp. Spilman, T.J., 1982. False powderpost beetles of the genus Dinoderus in North America (Coleoptera, Bostrichidae). Coleopterists Bulletin 36 (2), 193±196. Vrydagh, J.M., 1955. Contribution aÁ l'e tude des Bostrychidae (Coleoptera Teredilia) VII. Le genre Dinoderus Stephens 1830. Me moires de la Socie te Entomologique de Belgique, Bruxelles 27, 495±513. Wright, M., Akou-Edi, D., Stabrawa, A., 1993. Larger Grain Borer Project, Togo. Infestation of dried cassava and maize by Prostephanus truncatus: entomological and socio-economic assessments for the development of loss reduction strategies. Natural Resources Institute Report R 1941, Chatham Maritime, UK, p. 141.